The overdose-reversal drug Narcan is a lifesaver, but emergency doctors south of Boston are worried about what happens to drug addicts after the Narcan wears off.

The effects of Narcan last about an hour, meaning an overdose victim who decides to leave a hospital too soon after treatment could overdose all over again if opiate levels in the person’s body are still dangerously high.

“It is a very real challenge,” said Dr. Jason Tracy, who directs emergency medicine at South Shore Hospital in Weymouth. “But we are usually able to convince a patient who has just been brought back from a near-death experience to stay for the appropriate amount of monitoring to make sure they are safe to leave.”

In Brockton, doctors at Good Samaritan Medical Center sometimes offer hot meals to opiate overdose victims to try to get them to stay. They also warn them about the dangers of leaving too soon after emergency treatment.

An extra hour or two at the hospital reduces the chances of a patient overdosing again.

“The emergency department is the place where the drama plays out,” said Dr. Rick Herman, chief of emergency medicine at Good Samaritan. “If they’re near death we can bring them back to life. But the real issues extend way beyond the ER visit.”

Tracy said these patients need rehab, but there aren’t enough treatment beds available, nor are there enough mental health services available for those who need them.

“For somebody who wants to undergo a longer term treatment for their addiction, we have very limited options,” said Tracy. “We are doing a lot as a region to manage the acute overdoses, but we really need to consider our longer term plan for the patients we do reverse with Narcan.”

In 2013, South Shore Hospital treated 486 overdose victims in its emergency room, a 27 percent increase compared to 2012, when that numbers was 380. The majority of cases are opiate-related, said Tracy.

Patriot Ledger staff reporter Chris Burrell contributed reporting to this story. He may be reached at cburrell@ledger.com, or follow him on Twitter @Burrell_Ledger.